How many protons, neutrons, and electrons are present in each of the following atoms?
This is a very basic question. First, you know these atoms are neutral and the means the number of protons MUST equal the number of electrons. This is the case for any neutral compound, be it an atom or a molecule. The number of protons defines the identity of an atom (i.e. when chlorine is specified, the number of protons is 17 regardless of the mass. It follows that the number of electrons must be 17 as well) and can be easily taken from the periodic table. I (Iodine) has 53, K (Potassium) has 29 and Fe (Iron) has 26 protons. These numbers reflect the number of protons and electron since these compounds are neutral. To calculate the number of neutrons, all that is required is knowledge that the mass of one proton is 1 (AMU), which is identical to the mass of a neutron. The mass of the electron is neglected because it is insignificant incomparison to the proton or neutron. Since the mass numbers are provided, and we now know that atomic mass is the sume of the proton and the neutrons,
